Global Navigation Satellite System (GNSS) receivers use antennas to receive GNSS signals, such as L1, L2, and L5 signals, transmitted by GNSS satellites. One example of such an antenna is described in commonly owned U.S. Pat. No. 6,445,354 by Kunysz issued on Sep. 3, 2002 entitled, APERTURE COUPLED SLOT ARRAY ANTENNA, the contents of which are hereby incorporated by reference. The antenna, which radiates in both directions along its axis, may be made directional by the inclusion of a reflector that is strategically placed relative to the radiating component of the antenna. The directional slot antenna may be made from a printed circuit board (PCB) with a second PCB placed underneath and spaced from the antenna to act as a reflector to provide the antenna directivity and also to reduce back-lobe radiation.
Directional slot array antennas, which include directional pinwheel (PW) antennas, are designed with a reflector spacing between the radiating component of the antenna and the reflector. The reflector spacing height is related to the signal frequency or frequencies of interest and a desired gain. For example, to satisfy gain requirements at L1 and L2, the height of the reflector spacing is typically 15 mm. To satisfy the gain requirements at the lower frequency L5, the reflector spacing height needs to be larger, typically between 17 and 19 mm.
A disadvantage of prior directional PW antennas is that as the reflector spacing height is increased to satisfy desired gain requirements at lower frequencies, such as the L5 band, the overall size of the antenna necessarily increases. Enlarging the antenna to receive the L5 signals may require altering the configurations of devices that utilize the antenna. Further, consumer demand is typically for smaller electronic devices.
Accordingly, there is a need for an antenna that is capable of receiving lower frequency signals, such as L5 signals, that have dimensions similar or equal to the dimensions of an antenna that receives higher frequency signals such as L1 and L2. Additionally, there is a need for a smaller antenna that is capable of receiving the higher frequency signals, such as L1 and L2 signals.